Battery-Assisted RFID Tag Power Control and Interference Mitigation
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Solution Overview
Problem
RFID systems face limitations in range and reliability, especially for passive UHF tags, which are limited by power consumption and interference, and active systems are costly due to battery life constraints, necessitating an intermediate solution that enhances range and interference resistance.
Innovation Solution
The development of battery-assisted RFID systems with improved sensitivity and dynamic range states, using a transistor-based square law receiver and advanced command sets for interference control, power management, and selective dynamic range operation, allowing for scalable performance and interference resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive UHF RFID systems are used to reduce cost, then device complexity is reduced, but range and reliability are limited due to power consumption constraints
Solution Approach 1:
The patent combines the advantages of passive RFID (low cost, simple structure) with battery assistance (extended range, improved reliability) to create a hybrid system that achieves reliable operation without the full complexity and cost of active RFID systems
Solution Approach 2:
The system dynamically adjusts operating parameters including power levels, data rates, and modulation schemes based on channel conditions and battery status, allowing the tag to adapt between power-efficient and performance-optimized modes to maintain reliable operation
2Length of moving object
If active RFID systems are used to extend range, then range is improved, but cost increases due to battery life constraints and higher power consumption
Solution Approach 1:
The patent implements dynamic power management where the tag transitions between sleep, active listening, and full transmission modes based on communication needs and battery status, and the system adapts data rates and power levels in real-time to extend battery life while maintaining required communication range
Solution Approach 2:
The system varies operating parameters including transmit power, data rate, and modulation complexity based on distance from reader and battery remaining capacity, allowing extended range operation when needed while conserving power during normal operation
3Length of moving object
If higher transmit power is used to extend range, then range is improved, but interference to other systems increases
Solution Approach 1:
The patent implements dynamic power control where transmit power is adjusted in real-time based on measured channel conditions, distance to reader, and detected interference levels, allowing the system to use higher power only when necessary for range extension while minimizing interference to co-channel systems
Solution Approach 2:
The system uses feedback from signal strength measurements, error rates, and interference detection to continuously adjust transmit power levels, ensuring adequate range while preventing excessive interference to other RFID readers and wireless systems operating in the same or adjacent frequencies
4Adaptability or versatility
If multiple readers operate simultaneously in overlapping areas, then system versatility is improved, but interference between readers increases
Solution Approach 1:
The patent implements time-division multiplexing and periodic backoff protocols where readers take turns accessing tags in overlapping areas, with tags able to identify and respond only to their assigned reader during specific time windows, allowing multiple readers to operate simultaneously without mutual interference
Solution Approach 2:
The tag acts as an intermediary that receives signals from multiple readers, identifies the intended reader through synchronization codes and addressing, and selectively responds only to the correct reader, effectively mediating between multiple readers in overlapping coverage areas to prevent interference
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These systems achieve extended range and reliable operation across various environments while minimizing interference, offering a cost-effective alternative between passive and active RFID systems by optimizing battery life and performance.
Implementation Method 1
using a transistor-based square law receiver
Data Source
AI summary
A method for controlling RF power within an RFID system according to one embodiment includes returning a first set of RFID tags that were successfully accessed at a first reader forward mode power level to a hibernate state; initiating a timer operation in each of the RFID tags within the first set of RFID tags, the timer operation defining a period of time; and preventing the first set of RFID tags from responding to an activation command at a second reader forward power level during the period of time, the second reader forward power level being higher than the first reader forward power level; and wherein a flag state stored in each of the RFID tags within the first set of RFID tags indicates whether the timer operation is active to prevent undesired activation at the second reader forward power level.